Coral reefs & bleaching


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Coral reefs & bleaching

  1. 1. SC-249 Environmental Concepts & Issues Taichi Kikuchi
  2. 2. Outline1. What is Coral Reef?2. What is Coral Animal?3. Type of corals4. Phylum: Cnidaria5. The symbiotic relationship6. What is Coral Bleaching?7. Why do we have to care about Corals?8. How can we protect Corals from bleaching?9. Projects to survey and protect Corals10. References
  3. 3. What is Coral Reef? “The coral reef is a unique shallow water community of organisms living on limestone rock that was built by some of the reef organisms (Lerman 426).” The main reef builders are corals and coralline algae. Marine organisms that secrete calcium carbonate such as clams, snails and sponges accumulate to form reefs after their death. In other words, a reef is a clump of calcareous rock derived from diverse organisms living on the reef.
  4. 4. What is Coral Animal? Phylum : Cnidaria (same group as jelly fish, sea anemone) Corals inhabit in shallow, clear water within tropics. They have symbiotic tiny algae (zooxanthellae) within the body. In the daytime, they get nutrition via photosynthesis by zooxanthellae. They hunt for food at night with their tentacles. There are 215 scleractinian (58 genera) and 7 non- scleractinian corals in Palau (PICRC 12).
  5. 5. Type of corals Solitary (mushroom coral)/ colonial corals Stony corals: brain, staghorn, antler, lettuce, and flower coral → They secrete a cup-shaped skeleton of calcium carbonate, called corallite. Soft corals(octocorallia): seafans, sea pens, whip corals →They secrete soft, flexible skeletons made of keratin. Abundant stony corals in Pacific reefs. Abundant soft corals in Caribbean reefs.
  6. 6. Phylum: Cnidaria The classification of the major groups of coral animals
  7. 7. The symbiotic relationship Corals excrete their wastes to tiny algae. The tiny algae produce nutrition for coral polyps.
  8. 8. What is Coral Bleaching? Coral Bleaching = Corals which lost their symbiotic algae appear whitish. Corals are compelled to expel the algae because of its toxin when they are under stressful condition. Unusual high water temperature is thought as the main cause of the mass bleaching event in 1997~98. Some species can survive bleaching but the aftereffect includes slower growth, fragile body and higher risk of disease.
  9. 9. Why do we have to care aboutCorals? Ecological value: corals sustain rich marine biodiversity. (ex. Shelter for some animals, food for other animals Economical value: tourism, fishery industry (ex. Divers, tourists, and food supply Environmental value: they provide protection for us. (ex. Breaking storm wave, tsunami, typhoon Coral reefs have a great importance for Palau in many aspects.
  10. 10. How can we protect Corals frombleaching? Not to touch corals physically. Stop destructive actions such as dynamite fishing, over coastal development causing sedimentation. Have an interest on coral reef and take actions to spread knowledge. Proper instruction for any people trying to play around coral reefs.
  11. 11. Projects to survey and protectCorals The Marine Protected Areas (MPAs) = the place where people are prohibited or restricted to enter and use resources. PICRC National Long-Term Coral Reef Monitoring Program in 2001 ・21 monitoring sites around the main islands ・Coral reefs are recovering for 3 years from 2001. ・It suggests that some species are more resistant to pressure.
  12. 12. ReferencesMarshall, P and Schuttenberg, H. A Reef Manager’s Guide to Coral Bleaching. Townsville: Great Barrier Reef Marine Park Authority, 2006.Lerman, M. “Chapter 13 Coral Reefs.” Marine Biology. California: The Benjamin/Cummings Publishing Company, Inc, 1986.Palau International Coral Reef Center, and Japan International Cooperation Agency. Coral Reefs of Palau. Palau: Palau International Coral Reef Center, 2007.